Look inside the nipple and see if you can see a hex.  If so its adjustable. 

If it runs better with manifold vacuum I say leave it there.  Truthfully, I don't really worry about vac advance at idle.  I don't think I've ever even checked it.  I set base timing based on how much mechanical advance is in the distributor and my total timing goal.  So say the distributor is on the 13 slot in the breaker plate, which is 26 degrees of mechanical advance, and I want 38 degrees total; I set base timing at idle to 12 degrees.  Whatever the vac advance adds at idle doesn't mean much because it goes away the instant you floor it.  Vac advance is something you set at cruising speed.  Its the last thing you should mess with.  Get your base timing and curve set first, then you can go back and work on the vac advance.  I think you're worrying unnecessarily.  Especially if it idles well. 

Rudi wrote:

How many guys are running no vacuum advance. I know some of you are out there!

I have never tried running without vacuum advance. I run manifold vacuum adjusted to 8 degrees of advance at idle. I know the K codes had no vacuum advance; why I wonder.

Last edited by RV6 (4/13/2021 3:49 PM)

I ran a mechanical only distributor before I swapped to duraspark. Can’t tell much difference, but vacuum supposedly gives better mileage.

I recall my advance at idle with Duraspark was well over 40 degrees with vacuum connected to full port on carb.

I had thought that 36-38 would be max.

I took it to the only guy left in Portland that still has the equipment and know how to curve them and the first thing he found is that the vacuum mod leaked. I will have a curved Dissy tomorrow AM. At this point I mite just toss in the ol towel. Absolutely nothing has gone right with this engine. So why would it work now. All I wanted to do was put a fresh engine in the car and make it a great driver. it would make for a cool place to go sit outside and drink cool beverages in the front yard, maybe turn the trunk into a bar BQ and toss the hood and install a fish pond. Just a thought.

Life is better now. Got the re curved dissy back today. Set with 22 mech and dialed at 11. All comes in about 2500 He said the vac mod has 8, much much less than it had. I installed it and set the timing at 11. Car runs great and idles at 950 in nurt, drop in gear and it sits at 650 and can shake the whole car. This really runs a lot better. Took it out for a 40 mile cruse today and at 65-70 it holds a steady 200 degs. Even with the AC on. I have about 200 miles left until first oil change. Motor has had 3 oil changes in about 60 miles due to the mishaps. Water pump started to leak but I got a new better one on the way.

No its "around the block and busted". No really the car is running really strong now but it has not proved itself yet for any kind of road trips yet. had water pump take a dump waiting for replacement. Called the local speed shop and she said 289 sure no problem. I asked her if it was for early or late 289 and she said WHAT. I hung up